The source text provided should inform the user that the correct version of Plurality is not available. Instead, it complains that the section we want to replace is not present. This is confusing--the versioning error should take precedence over all other extension warnings.

Minimal Source Text To Reproduce

"Test"
Include version 12 of Plurality by Emily Short.
Test is a room.
Section - Fake (in place of Section - Faker yet in Plurality by Emily Short)
This is the fake rule:
do nothing.

An awkward timing issue, since at the time when Inform splices headings together, it hasn't yet worked out the versions it needs vs. the ones it has. I have reworded the problem message to be explicit about the version of the extension actually loaded:

Problem. In the sentence 'Section - Fake (in place of Section - Faker yet in Plurality by Emily Short)' , it looks as if you intend to replace a section of source text from the extension 'Plurality by Emily Short', but that extension does not seem to have any heading called 'Section - Faker yet'. (The version I loaded was 8.)